Spinneret



' 2 WV ATTORNEYS INVENTOR ARTHUR J. PRUTTON a5; BY

April 27, 1937. A. J. PR'UTTON SPINNERET Filed Feb. 13, 1954 Patented Apr. 27, 1937 UNITED STATES PATENT 'OFFICE SPINNERET Application February 13, 1934, Serial No. 711,024

7 Claims.

This invention relates to a spinneret of improved characteristics for spinning filaments, threads and the like, hereinafter referred to as artificial silk thread.

The invention in general aspect involves amon other things a plug fitting into a thimble-shaped spinneret which provides a number of fine perforations through which viscose, cuprammonium cellulose solution, cellulose acetate solution or nitrocellulose solution is forced prior to coagulation thereof. The plug has apassage therein of substantially smaller diameter than the inside diameter of the spinneret. It serves .to increase the velocity of flow of the solution in the spin-,

neret and also to cut down thetime during which the solutionis exposed to the heat of the setting bath prior to being spun. Certain other beneficial effects are obtained which will be setforth hereinafter.

As well understood, solutions from which artificial silk thread is spun, such as viscose, are squirted into a setting bath-through a spinneret which contains a number of very fine perforations having a diameter of the order of .003 to .004'of an inch; Particularly where viscose is being handled, small mounds or protuberances tend to build up aroundthe holes of the spinneret and particles of these may be subsequently broken off by the stream of viscose and carried into one or more of the perforations to cause interruption offiow. Where this occurs, the particular filament being formed by the stopped holeis interrupted and, even though the hole subsequently clears itself, an irregularity will be produced in the thread-constituted by the filaments. It is found that the formation of these mounds may be prevented and the inner surface of the spinneret kept clean by the ,means presently to be described.

1Another undesirable condition which the invention is intended to overcome is the effect of the heat of the spin bath upon the spinning solution in the spinneret. Particularly in the viscose process, in which the spin bath is maintained at a temperature of about 45 C., the heat of the spin bath has a tendency to coagulate the viscose andthus foul the spinneret. The pres ent invention reduces the time during which the solution to be spun is subjected to such heating and thus improves production.

It is, accordingly, an object of the present invention to provide a spinneret having improved operating characteristics. Another object of the invention is to provide a spinneret having an insert therein which increases the speed of flow of solution therethrough and thus tends to keep the inner surface of the jet clean. A further object of the invention is to provide an insert for spinnerets which reduces the time during which the solution is subjected to the heat of the spin bath before being spun. Further objects will in part be obvious and will in part appear hereinafter.

In the accompanying drawing there has been illustrated a preferred embodiment of the invention but it will be understood that the same is capable of modification to meet different conditions'without departing from the scope of the m vention. 1

1 In said annexed drawing, Fig. 1 is a perspective view of aspinneret, much enlarged; Fig. 2 is a, transverse section through a used spinneret showing the formation of mounds on the inner end surface of the spinneret; Fig. 3 is a perspective View, again much enlarged, of the spinneret insert of the present invention; Fig. 4 is a perspective view of a longitudinal section taken through a spinneret equipped with an insert; Fig. 5 is a fragmentary section through a spinneret showing a perforation and accompanying mound, further enlarged; and Fig. 6 is a vertical section through a spinning, apparatus showing a spinneret in operation.

Referring to the drawing, a spinneret l is made in the form of a cylinder with a flange 2 at the open end in order that the spinneret may be clamped to a carrier on the feed line. The spinneret is approximately thimble-shaped and is usually made of noble metal in order that it may resist corrosion in the spin bath, an alloy of 80% gold and 20% palladium being suitable. closed end 3 contains a number of minute perforations 4, forty being employed in the spinneret illustrated in the drawing, although this number may vary, through which viscose to be spun is forced by means of a pump 5. The viscose issues through the holes and is set up in a spin bath 6 to form as many filaments as there are holes in the spinneret. These filaments constitute a thread of the desired denier.

As the viscose passes through the mass tube 1, through the spinneret and into'the spin bath, it will be apparent that it remains for a definite period in the interior of the spinneret. During this time it is subjected to the heat from the spin bath, which, as stated, is maintained at about 45 C. It is known that heating tends to set up the viscose. Any tendency in this .directionflis likely to interfere with the flow of the solution through the extremely fine holes of the The,

spinneret. The viscose has been previously carefully filtered in order to screen out any solid particles which might block the perforations.

It is known that a spinneret gradually acquires mounds or protuberances 8 around each perforation, the cause of this not being definitely known, although there may be some connection between the formation of these mounds and the heating of the viscose solution which takes place inside the spinneret. Whatever the reason for the formation of these mounds, there is a likelihood that particles of the same will be broken off by the stream of viscose and swept into the perforations with consequent stopping of the flow of viscose therethrough. As mentioned above, such stoppage of any of the holes is undesirable. It results in the formation of irregularities on the surface of the thread, known as fish hooks in the trade. If the number of fish hooks is large, the grade of the yarn is reduced.

It has now been found that the inner end surface of the spinneret may be kept perfectly clean and the formation of fish hooks largely reduced by placing in the spinneret an insert 9, as shown in Fig. 3, this insert fitting closely into the spinneret and having a passage H therein. The effect is to increase the velocity of flow 01 the viscose within the spinneret, since it has a smaller area through which to pass and the' pressure on the feed line remains the same. This results in its remaining a shorter time within the spinneret, where, in ordinary practice, it can become heated through the thin metal walls of the spinneret. The insert also helps'insulate the viscose since the plug is preferably made of some non-conducting material.

The viscose is brought to the inner face of the perforated end 3 at one point and spreads out laterally to flow through the perforations, the insert having, if desired, a dished end E2 to provide a space connecting the perforations with the discharge orifice of the passage 1 i. This induces a more or less lateral fiow of the viscose which tends to sweep across the inner face of the spinneret and prevent the building upof the mounds 8. In this way, no solid material can accumulate around the perforations to constitute a source of particles which may be broken off and swept into the holes to stop the same. The opposite end of the plug may also be dished, as at 13, to render the insert reversible or to provide improved communication between the feed line and the passage H. The plug may be made of any suitable material, but nonconducting material such as hard rubber, bakelite or other artificial resin is found to be most satisfactory from the point of view of heat insulation and prevention of contamination of the viscose. However, the plug can be made of suitable metal or of other suitable materials, if desired.

The passage I I may vary in size but should be substantially less than that of the inside diameter of the spinneret in order to increase the velocity of flow therein. Good results have been obtained with passages ranging from to of an inch in diameter in a plug slightly less than inch in diameter, the diameter of the plug corresponding to the inside diameter of the spinneret. A A; inch hole thus causes substantially a sixteenfold increase in the velocity of flow through the spinneret. However, the orifice may be smaller or larger than this, as may be found to give the best results. In any event, it is desirable that the cross-sectional area of the passage, especially at the discharge end thereof, be at least as large as the. combined areas of the perforations in the spinneret in which the plug is inserted, in order to insure a sufiicient supply of spinning solution for all the perforations of the spinneret.

The yarn produced by the use of the new spinneret contained a considerably lower average number of fish hooks per dofi than when a spinneret without the insert is used. The strength of the yarn is not affected either as to wet or dry strength or elongation. It is also observed that no mounds are formed around the perforations in the spinneret containing an insert while, under the same conditions, control spinnerets containing no inserts show distinct rings surrounding the holes.

It is obvious that the embodiment of the invention here shown is susceptible of various modifications and that various other embodiments of the invention may be devised without departing from the spirit of the invention. It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

What I claim is:

l. A spinneret insert for use in the wet spinning of artificial silk thread comprising an approximately cylindrical plug adapted to be bodily inserted within and, when so inserted, to be encompassed throughout its length by the walls of a spinneret, saidplughaving its discharge end slightly dished and having extending therethrough a passage at least as great in cross-sectional area at its discharge end as the combined areas of the perforations of the spinneret in which said plug is intended to be inserted.

2. A spinneret insert for use in the wet spinning of artificial silk thread comprising an approximately cylindrical plug adapted to be bodily inserted within and, when so inserted, to be encompassed throughout its length by the walls of a spinneret, said plug having its ends slightly dished and having extending therethrough a passage at least as great in cross-sectional area at its discharge end as the combined areas of the perforations of the spinneret in which said plug is intended to be inserted.

3. Apparatus for the spinning of artificial silk thread comprising a spinneret having a plug bodily inserted in and encompassed throughout its length by the walls of said spinneret, said plug having extending therethrough a passage at least as great in cross-sectional area at its discharge end as the combined areas of the perforations of said spinneret.

4. Apparatus for the spinning of artificial silk thread comprising a spinneret having a plug bodily inserted in and encompassed throughout its length by the walls of said spinneret, said plug having extending therethrough a passage of substantially smaller cross-sectional area than the cross-sectional area of the interior of said spinneret.

5. Apparatus for the spinning of artificial silk thread comprising a spinneret having, bodily inserted in and encompassed throughout its length by the walls thereof, a plug characterized by a passage substantially smaller in crosssectional area than the cross-sectional area of the interior of said spinneret, said plug providing a space between the discharge end thereof and the perforated end of said spinneret.

6. Apparatus for the spinning of artificial silk thread comprising a spinneret having a plug bodily inserted in and encompassed throughout its length by the Walls of said spinneret, said plug its length by the walls of said spinneret, said plug having its discharge end slightly dished and having extending therethrough a passage substantially smaller in cross-sectional area. than the cross-sectional area of the interior of said 5 spinneret.

ARTHUR J. PRUTTON. 

